Compressive shrinking blanket and method for producing same



United States Patent COIVIPRESSIVE SHRINKING BLANKET AND METHOD FOR PRODUCING SAME Cato M. Littleton, Jr., Wilmington, N. C., and Carlton C. Gordon, Elsmere, N. Y., assignors to Albany Felt Company, Albany, N. Y., a corporation of New York No Drawing. Application April 30, 1953, Serial No. 352,288

12 Claims. (Cl. 117-55) This application is a continuation-in-part of the application Serial No. 317,149, filed by the said Cato M. Littleton, Jr., on October 22,1952.

This invention relates to mechanical fabrics such as are used in compressive shrinkage machines, Palmer machines, and the like, and more particularly to the felts or blankets used in such machines. Such fabrics are made from Wool or mixtures of wool with cotton or synthetic fibres.

The invention has special utility when applied to the felt blankets of compressive shrinkage machines, commonly known as sanforizing machines, which are used for the shrinking of textile fabrics such as cotton cloth, and will be described in connection with such machines.

One of the difliculties encountered in the practical use of these sanforizing or compressive shrinkage machines, in which the cloth to be treated passes through the machine in close contact with the felt blanket, is the fact that the blanket often leaves marks or creases on the cloth instead of giving it the desired smooth finish. The formation of these marks on the cloth is due to the fact that the outer surface of the felt fabric opens up as it is flexed in passing around the feed roller with the cloth in contact therewith, and then, as it passes to the main drum of the machine, with the cloth on the open side thereof, the cracks or openings in the surface of the blanket close, thus pinching'the cloth and producing undesirable marks thereon.

The principal object of the present invention is to provide a felt blanket of this character so treated that the marking of the cloth will be reduced to a minimum, and to this end the invention contemplates reducing the extent to which the felt opens up as it passes around the feed roller, but without reducing the longitudinal expansion and contraction of that surface of the blanket in contact with the cloth being treated which, of course, is necessary to preserve its shrinking function.

We have discovered that this object may be attained by treating the felt blanket with a chemical compound whichiwill have the property of softening and swelling and wool fibers of which the blanket is made and increasing the elasticity thereof, thus imparting to the felt the ability to stretch to a greater extent without opening than the untreated felt.

Not only does this softening and swelling reduce to a minimum the opening up of the convex surface of the felt as it passes around the roller of the machine, thus re ducing marking of the cloth, as above described, but it also provides a softer surface in contact with the cloth, and results in a smoother finish.

We have found that all polyhydric alcohols having molecular weights from about 62 up to about 600, and which are soluble in excess of about in a 50-50 mixture of isopropyl alcohol and water, are well suited for our purpose. One of these materials is dissolved in a relatively low boiling solvent, such as the aforesaid mixture of alcohol and water, and the blanket is thoroughly saturated with this solution. It is then dried at a temperature high enough to evaporate the solvent, but without significant loss of the polyhydric alcohol so that the latter remains in the felt and, as long as it remains therein, will maintain thewool fibers in their soft swollen condition.

The following polyhydric alcohols are among those which have the necessary characteristics set forth above and are suitable for use as swelling agents in carrying out the invention, namely,

Ethylene glycol Di'ethylene glycol Tri-ethylene glycol Poly-ethylene glycol up man average molecular weight of about 600.

Propylene glycol (all isomers; 1, 2 propanediol and 1, 3

propnanediol) Butylene glycol (all isomers; l, 2 butanediol; 1, 3 butanediol; l, 4 butanediol; and 2, 3 butanediol) Pentanediol (all isomers) Hexanediol (all isomers) Heptanediol (allisomers) Octanediol (all isomers) Glycerol Butanetriol (both isomers) Pentanetriol (all isomers) Hexanetriol (all isomers) Sorbitol We find that even as little as 1% of the foregoing polyhydric alcohols gives elasticity and hygroscopic qualities to felt blankets to a limited extent, but these qualities increase as the percentage is increased. In practice, we prefer to use from 3 or 4% up to about 15%, by Weight thereof, as compared with the weight of the blanket'being treated. We further find that any increase in the amount over about 20% has no perceptible eifect.

The above mentioned glycols are di-hydric alcohols, while glycerol is a tri-hydric alcohol. Sorbitol is mentioned as an example of 'hexahydric alcohol. Any of the polyhydric alcohols havingmolecular weights within the limits and soluble to the extent set forth above may be employed. All of those listed above have a boiling point of over C.

In applying some of these compounds to the fabric, it is necessary that the Wool fibers be swollen by being wet with water. This requirement may be met in several ways, such as using water'as part of the solvent for the polyhydric alcohol; or the'fabric may be wet with water and the excess Water removed by a centrifugal extractor, or in any other manner, after which the polyhydric alcohol may be applied by a spray, di'proll, or wiper roll, or impregnation of the fabric may be effected in any other way that will distribute the polyhydric alcohol fairly uniformly in the fabric.

Whether the alcohol is applied to the fabric by immersion, diprolls or 'roll coater mechanism, is immaterial. However, the swelling of the Wool fabrics with water is important because many of the polyhydric alcohols have molecules of such a size that they cannot penetrate'the pores of the fibers in the dry state. A moisture content in the blanket of approximately 30% or more, by Weight thereof, is suflicient to accomplish the swelling.

While the polyhydric alcohols alone give good results, We have found that the penetration and distribution thereof throughout the body of the felt is facilitated by adding to the solution a suitable wetting agent or surface active material. This wetting agent should have a boiling point Well above that of water so that no significant portion of it will be vaporized or driven off at the temperature necessary to evaporate the solvent. By thus leaving it in the felt, it also acts as a re-wetting agent when the felt is in use.

Wetting agents which are suitable are often known as re-wetting agents, namely, those which will remain incorporated in the fabric after it has been wetted and dried. We may use, by way of example, any of the following:

Ultra wet 60L (alkyl aryl sulfonate) Tergitols (sodium alkyl sulphates) Igepons (alkyl phenol ethylene oxide sulphates) Tritons (alkylated aryl polyether alcohols) Twitchells (alkyl aryl sulphonates) As an actual example, in the practical application of the invention, we take 8 to 12 pounds of di-ethylene glycol for every 100 pounds of felt being treated, and dissolve it in about 15 to 20 pounds of alcohol, such as isopropyl alcohol, mixed with sufiicient water to make a quantity of solution capable of thoroughly saturating the blanket being treated. For best results, we add 3 to 4 pounds of the wetting agents listed above, as, for example, Ultra wet 60-L.

The solution can be aplied in the final finishing operation of the felt manufacturer. Thus, it may be applied in the final rinse bath, and the felt then dried on a conventional drier.

Although the di-ethylene glycol is preferred on account of the relatively low price, any of the other compounds listed in the foregoing table may be used instead, in substantially the same amounts. Furthermore, ordinary ethyl alcohol may be used in place of the isopropyl, and any other neutral wetting agent may be substituted for Ultra-wet 60-L.

Due to the swelling of the fibers, in accordance with the invention, the opening up of the fabric, when flexed, is reduced to a minimum. This is due to the fact that the swelling of the fibers increases the diameter of the yarns, and causes them to occupy more space and lie closer together. Also, the softening of the fibers prevents them from imprinting or marking the cloth. Thus, blankets treated by our improved method, produce cloth substantially free from blanket marks, and with an exceptionally smooth finish. The softening and swelling of the fibers also hate the effect of rendering the felt more elastic and increasing its ability to stretch without breaking.

Sanforizing or compressive shrinkage blankets are made in different wei hts or thicknesses, to suit different types of cloth, and ordinarily, the heavier the blanket, the more it tends to mark the cloth. Therefore, the lightest blanket capable of properly finishing the particular type of cloth being handled in chosen. Since, however, it is impractical to change blankets on a machine for each different type of cloth being finished, the operator usually comprises by choosing a weight of blanket best suited, on the average, for several different styles of cloth.

By treating the blanket in accordance with the present invention, we are enabled to use a blanket heavy enough properly to finish all styles of cloth without markings, that is to say, the invention makes it possible to employ a blanket heavier than would normally be used, namely, a blanket so heavy that, if untreated, it would definitely impair the finish of certain styles of cloth.

Thus, our invention makes it unnecessary to change blankets when shifting from one group of cloth styles to another, since a treated blanket heavy enough to handle the style of cloth requiring a heavy blanket, can be successfully used to finish many other styles of cloth normally requiring a lighter blanket.

While we have described the invention with special reference to felt blankets for sanforizing or compressive shrinkage machines, it is applicable, in its broader aspects, to blankets of Palmer machines.

A Palmer machine is very similar to a sanforizing ma chine, except that it does not serve to shrink the cloth. It is used chiefly for giving a smooth finish to rayons and silks. A Palmer machine blanket processed in accordance with the present invention will produce better finished, smoother goods.

Where, therefore, in the appended claims, we use the expression compressive shrinkage or like machines, we mean to include Palmer machines. Furthermore, by the term polyhydric alcohol we intend to include not only those compounds in which the hydroxyl groups are at tached to a straight carbon chain, as exemplified by butylene glycol, but also those in which the carbon chain contains one or more ether linkages such as in diethylene glycol.

What we claim is:

1. The method of treating an endless, woven and fulled blanket formed substantially of wool and of the type used for the compressive shrinkage of other fabrics, to reduce the extent to which the convex surface of said blanket will open when flexed in passing around the feed roller of a compression shrinkage machine; said method comprising impregnating said blanket with a .polyhydric alcohol of a molecular weight from about 62 to about 600 and soluble in excess of about 5% in a 50-50 mixture of isopropyl alcohol and water; whereby, marking and creasing of the fabrics shrunk by said blanket are substantially eliminated.

2. The method set forth in claim 1 in which the alcohol is (ii-ethylene glycol.

3. The method of treating an endless, woven and fulled blanket formed substantially of wool and of the type used for the compressive shrinkage of other fabrics, to reduce the extent to which the convex surface of said blanket will open when flexed in passing around the feed roller of a compression shrinkage machine; said method comprising impregnating said blanket with a solution of a polyhydric alcohol having a boiling point above C. in a solvent having a boiling point at least 30 degrees lower than that of the alcohol; and thereafter removing said solvent from said blanket by evaporation thereof at a temperature which will leave substantially all of said alcohol incorporated in said blanket; whereby, marking and creasing of the fabrics shrunk by said blanket are substantially eliminated.

4. The method of treating an endless, woven and fulled blanket formed substantially of wool and of the type used for the compressive shrinkage of other fabrics, to reduce the extent to which the convex surface of said blanket will open when flexed in passing around the feed roller of a compression shrinkage machine; said method comprising impregnating said blanket with a solution of diethylene glycol in a solvent comprising alcohol and water; and thereafter evaporating the solvent at a temperature below the boiling point of the di-ethylene glycol; whereby, the major portion of the di-ethylene glycol remains incorporated in said blanket, and marking and creasing of the fabrics shrunk by said blanket are substantially eliminated.

5. The method of treating an endless, woven and fulled blanket formed substantially of wool and of the type used for the compressive shrinkage of other fabrics, to reduce the extent to which the convex surface of said blanket will open when flexing in passing around the feed roller of a compression shrinkage machine; said method comprising impregnating said blanket with a solution of polyhydric alcohol together with a wetting agent having a high boiling point, in a solvent having a relatively low boiling point; and thereafter evaporating the solvent at a temperature substantially below the boiling points of both the polyhydric alcohol and the wetting agent; whereby, said alcohol and said wetting agent will remain in said blanket, and marking and creasing of the fabrics shrunk by said blanket are substantially eliminated.

6. The method of treating a compressive shrinking blanket comprising an endless, woven and fulled structure formed substantially of wool to reduce the extent to which the convex surface of said blanket will open when flexed in passing around the feed roller of a compressive shrinkage machine; said method comprising first, swelling the wool fibers of said blanket by treating said blanket with water; then, applying to said blanket a polyhydric alcohol having molecules of a size which will penetrate said swollen fibers; and thereafter substantially removing the water from said fibers while allowing most of said alcohol to remain therein and maintain said fibers in swollen condition.

7. A compressive shrinking blanket comprising an endless, woven and fulled fabric characterized by the smoothness and continuity of its convex side when flexed, as in passing around the feed roller of a compressive shrinkage machine; said fabric being formed in substantial part of wool fibers impregnated with a polyhydric alcohol.

8. A compressive shrinking blanket comprising an endless, woven and fulled fabric characterized by the smoothness and continuity of its convex side when flexed, as in passing around the feed roller of a compressive shrinkage machine; said fabric being formed in substantial part of wool fibers impregnated with di-ethylene glycol.

9. A compressive shrinking blanket comprising an end- 20 less, woven and fulled fabric characterized by the smoothness and continuity of its convex side when flexed, as in passing around the feed roller of a compressive shrinkage machine; said fabric being formed in substantial part of wool fibers impregnated with glycerol.

10. A compressive shrinking blanket comprising an endless, woven and fulled fabric characterized by the smoothness and continuity of its convex side when flexed, as in passing around the feed roller of a compressive shrinkage machine; said fabric being formed in substantial part of wool fibers impregnated with a substance selected from the group consisting of the diols, triols and polyols.

11. A compressive shrinking blanket comprising an endless, woven and fulled fabric characterized by the smoothness and continuity of its convex side when flexed, as in passing around the feed roller of acompressive shrinkage machine; said fabric being formed in substantial part of wool fibers impregnated with a polyhydric alcohol having a molecular weight from about 62 up to about 600 and soluble in excess of about 5% in a -50 mixture of isopropyl alcohol and water.

12. A compressive shrinking blanket comprising an endless, woven and fulled fabric characterized by the smoothness and continuity of its convex side when flexed, as in passing around the feed roller of a compressive shrinking machine; said fabric being formed in substantial part of wool fibers impregnated with a polyhydric alcohol and a wetting agent having a high boiling point.

References Cited in the file of this patent UNITED STATES PATENTS 77,138 Warren Apr. 21, 1868 1,852,891 Whitehead Apr. 5, 1932 1,872,913 Dreyfus Aug. 23, 1932 2,051,389 Nuesslein Aug. 18, 1936 2,629,674 Ericks Feb. 24, 1953 

3. THE METHOD OF TREATING AN ENDLESS, WOVEN AND FULLED BLANKET FORMED SUBSTANTIALLY OF WOOL AND OF THE TYPE USED FOR THE COMPRESSIVE SHRINKAGE OF OTHER FABRICS, TO REDUCE THE EXTENT TO WHICH THE CONVEX SURFACE OF SAID BLANKET WILL OPEN WHEN FLEXED IN PASSING AROUND THE FEED ROLLER OF A COMPRESSION SHRINKAGE MACHINE; SAID METHOD COMPRISING IMPREGNATING SAID BLANKET WITH A SOLUTION OF A POLYHDRIC ALCOHOL HAVING A BOILING POINT ABOVE 150* C. IN A SOLVENT HAVING A BOILING POINT AT LEAST 30 DEGREES LOWER THAN THAT OF THE ALCOHOL; AND THEREAFTER REMOVING SAID SOLVENT FROM SAID BLANKET BY EVAPORATION THEREOF AT A TEMPERATURE WHICH WILL LEAVE SUBSTANTIALLY ALL OF SAID ALCOHOL INCORPORATED IN SAID BLANKET; WHEREBY, MARKING AND CREASING OF THE FABRICS SHRUNK BY SAID BLANKET ARE SUBSTANTIALLY ELIMINATED. 